Electromagnetic sentinel



UNITED STATES PATENT OEEICE.-

.y IRANoIs B. nAD'r, or CHICAGO, ILLINOIS.

IELECTFOVMAGNETIC SENTINEL.V

SPECIFICATION forming part of Letters Patent No. 571,739, dated November 24, 1896.

Application and February 15, 1896. serai No. 579,4 4a (No model.)

9,) of which thel following is a full, clear, concise, and exact description, reference being had to the accompanying drawings, forming a part of this specification.

My invention relates to an electromagnetic sentinel for detecting the approach of a mass of magnetic material, and more particularly.

arm or-cla-d war-ships.

The special object of my invention, is to provide a device readily stationed in commanding positions that will automatically give warning of the presence of battle --ships vin `that vicinity, and thereby enable a submerged mine or torpedo to be exploded by a switch operated either by hand or automatic means at the moment the hostile vessel is above such explosive.

The best method heretofore employed for coast protection by means of explosive minos has been eto sink them in the waterway desired to be protected, but preferably in a narrow channel,and from two Observatories upon shore connected by telephone and telegraph vby means of range-finders the oiiicers on duty follow the movements of any hostile vessel. When the instruments indicate the said vessel is directly above the hidden mine by means of. a switch operated either automat- Aically or by hand, controlling a source of powerful electric current, the mine is exploded. This method, however, is subject to the objection of 'the high cost of such protection,

as two Observatories and setsvof instruments.

and 'two or more operators of such instruments are necessitated. The apparatus above- Adescribed is also somewhat unreliable, as it is quite easily disordered aand thereby liable to be rendered inoperative and can be-used to follow the movements of but one vessel at a time. -At night or during the prevalence of fog, storms, or any other condition tending to obstruct thevisi'on its usefulness is greatly limited ora-ltogether impaired. On"

the contrary, the device of my present application is 'automatic Ain its action and gives its warnings by night as well as by day. It is simple and direct in its operation and requires but a single observatory, set of instruments, and attendant, or it may be so constructed as vto automatically explode the mine iu addition to signaling the vessels presence. f

The device about to be described consists of an induction-coil'the core of which is an open magnetic circuit, the terminals of the coil being connected with a source of alternating or interrupted current, and suitable indicating devices situated within an observatory' upon shore. The indu ction-coil of thedevice may be secured to a mine or torpedo which is provided witli a fuse which can be connected with the source of a powerfulelectric current by a switch operated at the observatory.

Referring to the 4drawings accompanying this application, Figure l is a diagrammatic view of the device attached to a mine provided witli a hand-switch for the explosion of the mine. Fig. 2 is asimilar view showing anarrangement for the automatic explosion of the mine. Fig'. 3 is a diagrammatic View of the device in which a telephone is substituted for the indicating device.

Like letters refer to like parts in the several figures.

The induction-coil a., with its core b, constituting an open magnetic circuit, is attached to the'submerged mine and is electrically connected with the instruments'in the observatory -upon shore by the insulated wire 0, ground connections being made at d and d. Within the observatory is a source of interrupted or.v alternating current c', which constantly iiows through the induction-coil'wh en the apparatus is in operation. There is also provided at the observatory in this 4circuit a suitable 'current measuring instrument f,

adapted to give warning whenever a variation in the current occurs. A powerful source o f electric current h, adapted lto explode the mine by means of fuse lo, which oifers a high inductive resistance, is arranged to becut into circuit therewith by means of the switch g under the control of the officer on duty, or

may be operated automatically by the indicator device, as illustrated in Fig. 2, showing the circuit h h2, adapted to be closed at contact g by the arm of the indicator, while the ing the contact Z from the mercury in the l dash-pot nz.

It is evident that with such a device situated in the course of any modern War vessel heavily protected by iron or steel armor the p approach thereof within the path of the open magnetic circuit ot the coil will increase the self-induction ot' the said lcoil and less current will flo-vv through the circuit. The indicating device at the observatory will denote to the officer on duty such decrease in current by appropriate means, Whose attention being directed to the vessel the said otiicer can at the proper .moment close lthe fuse-circuit and explode the mine 0. vIncase an automatic device bc similarly employed, as mentioned above, the arm of the indicator will be deflected until ing'contact with point g and the explosion will resul-t.

l? or some purposes an all metallic circuit might be found desirable, which change could, of course, be made at a slight additional cost. In Fig. a telephone n has been introduced into circuit for the detection of current variation in place of other indicating device, which would be denoted to the officer by the change in tone caused thereby in the instrument.

A slight modification ol.' the device, as illustrated in `Fig. 2, is easily applicable to the self-propelling tgvpe of torpedo, being so constructed as to explode the same when within effective distance of any hostile ironclad, and thereby doing away with the necessity of actual contact of the torpedo With the vessels hull, Which would serve to render the torpedo more effective. i

The means for locating the coil with open magnetic circuit so that the ironclad ship or other movin g magnetic mass shall come Within its lield constitutes no part of my invention, and I do not think it necessary to describe it.

'hilc the particular object-of my invention is, as I have already said, its application to coast defense with the view of determining the proximity oi' ironclads to submarine mines, it is obvious that there are other applications of the invention, and I do not wish to limit myself to this precise object.

Having thus described my invention, what I claim as new, and desire to secure by Letters Patent, is*

l. In a vsigna-l device, the combination with a coil having its core in open magnetic eircuit, of a source of alternatingor interrupted current passing through the said coil, and an indicator provided within the circuit of the said coil adapted to indicate any current variation therethrough, substantially as described.'

2. In a device for the detection of approaching iron or steel clad vessels, the combination with a submerged mine or torpedo 0, oi' a coil u., attached to the same, whose core 11 is an open magnetic circuit, a source oi altermating or 'interrupted current e flowing through the said coil, acurrent-indieatin g device f adapted to' give warning when any change in current through the said coil takes place, a source of high potential electric current adapted to explode thc said mine or torpedo, amlmcans for switching the said current into circuit therewith5 substantially as described.

In Witness whereof I hereunto subscribe my naine this' 12th day of February; A. D. 1896.'

FRANCIS B. BADT.

Witnesses:

CHARLES A. BROWN, JOHN W. StNcLAIR. 

